Here's the science explaining why Friday night will bring freezing rain and not snow

Why a forecast of freezing rain and not snow?
Posted at 10:52 AM, Jan 13, 2017
and last updated 2017-01-13 10:52:40-05

CINCINNATI -- The set-up for Friday night's wintry mess is one that favors freezing rain and not snow. So what’s going on the atmosphere that allows for freezing rain? It’s all about this thing in the weather world called a “temperature profile.”

Let’s dive into the science behind the ice.

Let’s start at the top of our temperature profile: the cloud level. Temperatures are much colder where clouds are releasing precipitation than they are here at the surface. Any precipitation that falls from them at this level is in the form of snow.

As the snowflake falls, it will stay a snowflake as long as the temperature stays below 32 degrees. If the temperature from the cloud level to the surface (the temperature profile) stays below 32 degrees the entire time, the snowflake will remain a snowflake. That will not be the case Friday into Saturday.

Once the snowflake falls somewhere between 3,000 and 10,000 feet, the air temperature is expected to rise to around 40 degrees. This will melt the snowflake, changing it into a raindrop. Now we have a raindrop falling to the ground instead of a snowflake.

Down here at the surface, temperatures are expected to hover around 32 degrees. Given that this is a very shallow area of cold air, the raindrop will not have enough time to freeze as a sleet pellet. The raindrop will make it to the ground and gradually freeze, forming a thin glaze of ice. This is freezing rain.

The graphic below illustrates the temperature profile our system will be working with. You can see the snowflake starts at the cloud level, then falls into the warmer layer below where it switches to rain, then falls into the surface cold layer and freezes on the ground.